An observation of the quantity of the analyte found within the sample. Note that loinc and procedure codes are identifying more specifically the type of test being performed. Because there may be multiple methodologies available to measure the same substance, these codes are more specific than the analyte and testCode referenced in the ChemistryTest class. Note that this class has 5 subtypes to handle the different kinds of result values. Most chemistry tests are physical quanties (e.g., mg/dL). Some are coded, and even those that normally are physical quantities might be replaced by a coded observation of Quantity Not Sufficient.